Chain pipe wrench



Jan. 17, 1967 KENZO Y M E 3,298,258

CHAIN PIPE WRENCH Filed April 19, 1965 INV EN TOR.

KENZO MIYAMAE is turned to the desired extent.

United States Patent CHAIN PIPE WRENCH Kenzo Miyamae, 539-6 Hishiya Higashi, Fuse, .lapan Filed Apr. 19, 1965, Ser. No. 449,235 3 Claims. (Cl. 81-68) The present invention relates to a chain pipe wrench and, more particularly, to such a wrench having a device or attachment adapted to improve its performance, facilitate use, and ensure safety in operation. The significant element of the ratchet wrench of the present invention consists in a retaining cap mounted over a partial length of the roller chain used in the ratchet wrench. As will hereinafter be fully described, said retaining cap serves to keep the chain stretched taut at all times and help the chain to brace the pipe to be turned.

The pipe wrench of the conventional type consists of a lever having a gripping head and a roller chain, and s so adapted that, when a pipe is to be turned, the chain is passed around the pipe and secured in hooks on the underside of the lever. The lever is then pressed down wards so as to cause teeth in the gripping head to bind against the pipe, thereby increasing the friction at the contact between pipe and chain and placing a torque on the pipe. This arrangement is disadvantageous in that when the operator pulls the lever upwards after a cycle of turning and before starting to press down the lever a second time for further turning of the pipe, the chain 18 slackened and, consequently, the chain quite frequently detaches itself from the hooks on the head. When this occurs, the operator must reset the chain around the pipe and hook it up again. Sometimes, it requires several cycles of such resetting and re-hooking before the pipe In accordance with the present invention, the above-mentioned disadvantage may be completely eliminated as will be described hereinafter in detail.

A primary object of the present invention is to provide a simple means whereby the chain of the wrench may be kept taut during the entire turning operation, that is to say, over several cycles of lever operation.

Another object is to provide a means whereby the pipe wrench of the conventional type may be considerably improved easily and at nominal additional cost. Other ob ects and advantages of the present invention will become clear as the following description proceeds, reference being had to the accompanying drawings, in which:

FIG. 1 is an elevation view showing the pipe wrench of the invention in operation; and

FIG. 2 is a plan view of the same wrench as above as seen from above.

Referring, now, to FIGS. 1 and 2, the ratchet wrench has a lever 1 which is provided with a cranked head 2, the upper surface of which is toothed as indicated by numeral 3. The lever 1 has, on its upper side, a pair of projections 4, 4' adapted so that the base end 5 of a roller chain 6 may be interposed therebetween and securely locked in position by means of a link pin 7. A retaining cap 8 is pivotally mounted on the projection 4, 4 of said lever 1 through the intermediary of a link pin 9 in such a manner that the free end of the cap 8 is pressed downwards at all times by the action of a coil spring 10 built into the cap and around said link pin 9, it being understood that the retaining cap may be spring-loaded in any other manner, if desired. The length of said retaining cap 8 is substantially optional, e.g. the equivalent of several chain links or greater, although it is subject to practical limits.

The roller chain 6, except the length of several links f o it base end 5, is provided with pins 11, one for each link. A pair of hooks 12, 12', which are adapted to engage "ice said pins 11, is provided on the under-side of the head 2 of the lever 1 in such a manner that a groove 13 is formed between said hooks 12, 12, which preferably are formed integrally with the crank-ed head 2 for sufiicient strength.

In operation, the roller chain 6 is first passed over a pipe A to be turned and the end opposite the pivot end of cap 8 is rested against the top of the pipe. When the operator presses down and forward on the lever 1 the cap slides along the pipe obliquely upwards in the direction of arrow a and pivots away from the lever and with the teeth 3 of its head 2 come in to intimate contact with the pipe A. The roller chain 6 which is provided with pins ll is then stretched tightly around the pipe and the pins 11 closest to the hooks 12, 12' are engaged with the hooks. In this state, the pipe A is securely held in position by the retaining cap 8, roller chain 6, and toothed head 2. If, then, the operator presses the lever ll downwards in the direction of arrow 0, the pipe A is turned in the direction indicated by arrow b as the tooth head 2 binds on the pipe. When this cycle of lever operation is completed the operator may raise the lever to cause the teeth 3 to come again into a new contact with the pipe.

Essentially speaking, what differentiates the pipe wrench of this invention from that of the conventional type is the provision of the above-mentioned retaining cap. This cap cooperates with the pipe and toothed head to retain the chain securely in position. This cooperation is effected as the retaining cap presses the pipe at contact point P (FIG. 1). Since the angle between contact point P and teeth 3 with respect to the center C of the pipe is always smaller than degrees, the pipe A tends to be pushed outwards or farther away from the operator or, if the pipe is immovable, the wrench tends to 'be pushed away from the pipe. In either case, the chain is held taut and disengagement from the hooks is prevented. This arrangement is of greater practical value than might be generally considered. For, it is common experience with the conventional pipe wrench that when the operator pulls the lever upwards before entering into a fresh cycle of turning, the chain quite frequently detaches itself from the books. This detachment not only interrupts the operation but also can cause injuries. To prevent this undesirable occurrence, the operator usually has to pull the lever forcefully toward himself lest the chain should be slackened and disengaged. Moreover, he sometimes has to control the tension of the chain by hand so as to carry the turning operation to completion. In accordance with the present invention, the roller chain is held in substantially intimate contact with the pipe owing to the outward component of the force exerted by the retaining cap through the spring upon the pipe at contact point 1 (FIG. 1) even when the lever is being raised. In the arrangement thus far described, it will be obvious that the chain is prevented from being detached from the hooks so that the turning of the pipe may be carried out continuously without fear of detachment of the chain.

The ratchet wrench of the present invention has an additional advantage of great importance in that even when the wrench is substantially large it can be easily used just as in the case of a much smaller wrench. Furthermore, the pipe wrench of this invention accommodates pipes of fairly large diameter which have never been successfully turned with the conventional wrench of the same size. This is because the frictional force applied by the retaining cap to the pipe at contact point P augments the engaging action of the teeth and chain of the wrench. In addition, when the wrench is to be removed from the pipe after operation, it is sufficient for the operator to grip the lever with one hand near the teeth end and one to the rear and push it forward and downward without pivoting. When the lever is thus pushed, the retaining cap slides obliquely upwards in the direction of arrows at so that the chain is slackened sufiiciently to disengage the above-mentioned attachment in the hooks of the wrench. This disengagement occurs instantly and automatically, and this feature is particularly beneficial when the wrench is of large size and also when the pipe is not easily accessible. Moreover, when the wrench is stored 'or carried about, the retaining cap serves to prevent the chain from swinging and being entangled. This feature is also of great practical value, for it is not only conducive to the prevention of accidents but also assists in the maintenance of the wrench.

What I claim as my invention:

1. A chain pipe Wrench for turning a pipe, comprising: a lever having a pipe binding head; said head having at least one toothed pipe engaging surface on its upper side and a pair of hooks situated laterally spaced on its underside; a roller chain pivotally fixedly attached at one end to said lever away from its head and having a length greater than the length of the path extending from the point of attachment around a pipe engaged in a region on said toothed surface to said hooks; said hooks spaced a distance exceeding the width of said chain, said chain having pins protruding transversely from its links to engage in said hooks; a retaining cap pivotally connected pressing the cap against the pipe.

2. A chain pipe Wrench as claimed in claim 1, said retaining cap having a concave cross section of an internal Width larger than the width of said chain, said cross section open towards the lever and surrounding said chain.

3. A chain pipe wrench as claimed in claim 2, said pins located only in the length of said chain outside of said retaining cap.

References Cited by the Examiner UNITED STATES PATENTS 1,410,993 3/1922 Carll 8168 1,470,161 10/1923 Gray 8168 2,795,986 6/1957 Petersen 8168 WILLIAM FELDMAN, Primary Examiner.

JAMES L. JONES, ]R., Examiner. 

1. A CHAIN PIPE WRENCH FOR TURNING A PIPE, COMPRISING: A LEVER HAVING A PIPE BINDING HEAD; SAID HEAD HAVING AT LEAST ONE TOOTHED PIPE ENGAGING SURFACE ON ITS UPPER SIDE AND A PAIR OF HOOKS SITUATED LATERALLY SPACED ON ITS UNDERSIDE; A ROLLER CHAIN PIVOTALLY FIXEDLY ATTACHED AT ONE END TO SAID LEVER AWAY FROM ITS HEAD AND HAVING A LENGTH GREATER THAN THE LENGTH OF THE PATH EXTENDING FROM THE POINT OF ATTACHMENT AROUND A PIPE ENGAGED IN A REGION ON SAID TOOTHED SURFACE TO SAID HOOKS; SAID HOOKS SPACED A DISTANCE EXCEEDING THE WIDTH OF SAID CHAIN, SAID CHAIN HAVING PINS PROTRUDING TRANSVERSELY FROM ITS LINKS TO ENGAGE IN SAID HOOKS; A RETAINING CAP PIVOTALLY CONNECTED AT ITS BASE-END TO SAID LEVER; SAID CAP EXTENDING FROM ITS BASE END TO BEAR WITH ITS OTHER END IN SLIDING CONTACT ON A POINT OF THE PIPE LOCATED AT AN ARC GREATER THAN 0 AND LESS THAN 180* FROM THE REGION OF ENGAGEMENT OF THE TOOTHED SURFACE, THE ARC MEASURED ABOUT THE PIPE AXIS AS VERTEX ON THE PERIPHERY OF THE PIPE FACING THE PIVOT; AND A SPRING CONNECTED BETWEEN THE LEVER AND THE CAP, PRESSING THE CAP AGAINST THE PIPE. 